The effect of muscle length on intracellular calcium and force in single fibres from mouse skeletal muscle

被引:100
作者
Balnave, CD [1 ]
Allen, DG [1 ]
机构
[1] UNIV SYDNEY, DEPT PHYSIOL, SYDNEY, NSW 2006, AUSTRALIA
来源
JOURNAL OF PHYSIOLOGY-LONDON | 1996年 / 492卷 / 03期
关键词
D O I
10.1113/jphysiol.1996.sp021339
中图分类号
Q189 [神经科学];
学科分类号
071006 ;
摘要
1. The effect of muscle length on the myoplasmic free Ca2+ concentration ([Ca2+](i)) and tetanic force production of intact single muscle fibres was investigated in the mouse flexor brevis muscle. Muscle fibres were analysed at 100 mu m intervals from 100 mu m shorter than the optimum length (L(0)) to 300 mu m longer than L(0). The fluorescent Ca2+ indicator indo-1 was used to measure [Ca2+](i). 2. Changes in muscle length did not significantly affect tetanic or resting [Ca2+](i). However, at lower stimulus frequencies (30-50 Hz) the force-length relation was shifted to longer muscle lengths. 3. Force-tetanic [Ca2+](i) curves were constructed at each muscle length. A comparison of these curves revealed that the Ca2+ sensitivity was length dependent. Ca2+ sensitivity increased over the ascending limb and plateau phase of the force-length curve, but over the descending limb Ca2+ sensitivity reached a plateau and then started to decrease once more. 4. These results show that length-dependent changes in Ca2+ sensitivity of single muscle fibres cannot simply be related to variations in sarcomere length. It is proposed that other factors, such as cross-bridge attachment and/or developed force, have a role in determining the Ca2+ sensitivity at a particular muscle length.
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页码:705 / 713
页数:9
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